<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
   
  <div id="app"></div>

  <template id="why">
    <div>
      <h2>{{message}}</h2>
      <h2>{{counter}}</h2>
      <button @click='increment'>+1</button>
      <button @click='decrement'>-1</button>
    </div>
  </template>

  <script src="./js/vue.js"></script>
  <script>
    Vue.createApp({
      template: '#why',
      data: function() {
        return {
          message: "methods中的this",
          counter: 100
        }
      },
      methods: {
        // 1.箭头函数
        increment:()=>{
          this.counter++;
          console.log('increment=>', this)
        },
        // 2.function函数简写
        decrement() {
          this.counter--;
          console.log('decrement=>', this)
        },
        // function函数完整写法
        // decrement:function() {
        //   this.counter--;
        // },
      }
    }).mount('#app');

  </script>
</body>
</html>